Application of Image Guidance Technology to Bedside External Ventricular Drain Placement

External ventricular drain (EVD) placement is performed very often in neurosurgical practices. EVD's are used most commonly to monitor intracranial pressure and divert cerebrospinal fluid (CSF) in patients with increased intracranial pressures. Pathologies where EVDs are most frequently needed include hydrocephalus, malignancy, and/or trauma. EVD's are most commonly placed at the bedside using external anatomical landmarks to guide the catheter into the frontal horn of the ipsilateral lateral ventricle. EVDs are often placed due to acute neurological compromise and require timely insertion. This can increase the associated risk and result in complications.

Accurate catheter placement is essential to achieving effective external CSF drainage without complications or occlusion/failure of the catheter. Catheter placement is most commonly performed via a freehand approach using external anatomical landmarks to help identify the location of the lateral ventricle within the brain without the aid of imaging. Proper identification of the ventricles on pre-procedure imaging, surgeon skill, and estimation of pathologic perturbations to the normal location of the ventricles all factor into the success of catheter placement. Multiple passes are often required. The accuracy rate from the freehand technique has been reported to range from 40 to 98 percent. A very basic grading scale has been developed to assess placement but does not include items such as the number of passes until successful placement and presence of post placement hemorrhage or other neurological complications. An increased number of passes increases the risk of post placement hemorrhage and may damage the brain. Hemorrhage has been reported to occur after catheter placement at rates ranging from 0.2 to 41 percent.

Current methods for EVD placement do not compensate for superficial brain vessels or pathology that may alter the intracranial anatomy such as trauma, hemorrhage, or mass lesions. Some studies have attempted to use CTA imaging to identify intracranial vessels in an attempt to avoid them during placement.

Image guidance is a tool used very commonly for placement of EVD's and shunts in the operating room. AxiEM Stealth is a noninvasive image localization modality that registers a CT or MRI to the individual patients facial and scalp anatomy. A probe can then be used to identify, in real-time, the underlying anatomy and trajectories. This imaging guidance may improve the accuracy of EVD placement.

This study will compare the current standard of care of freehand placement of bedside external ventricular catheters to the placement of EVD catheters with AxiEM Stealth image guidance. Accuracy of the tip of the catheter, occurrence of post-placement hemorrhage, the number of passes required for CSF flow, ventricle diameter, catheter clogging/failure, time required for placement, patient demographics and other secondary outcome measures such as Glasgow Outcome Scale (GOS) and Modified Rankin Score (MRS) will be collected. The hypothesis is that image guided EVD catheter placement will improve accuracy, decrease the number of brain transgressions, and decrease complications of EVD placement.